Micro LED Display Panel, Manufacturing Method Thereof and Display Device

The present disclosure claims the benefits of priority to PCT Application Nos. PCT/CN2024/134859, PCT/CN2024/134869, PCT/CN2024/134878, PCT/CN2024/134881, PCT/CN2024/134886, PCT/CN2024/134890, and PCT/CN2024/134893, all filed on Nov. 27, 2024, and all of which are incorporated herein by reference in their entireties.

The present disclosure generally relates to micro display technology, and more particularly, to a micro LED display panel, a method of manufacturing the micro LED display panel, and a display device.

Inorganic micro pixel light emitting diodes, also referred to as micro light emitting diodes, micro LEDs, or μ-LEDs, become more important since they are used in various applications including self-emissive micro-displays, visible light communications, and optogenetics. The micro LEDs have higher output performance than conventional LEDs because of better strain relaxation, improved light extraction efficiency, and uniform current spreading. Compared with conventional LEDs, the micro LEDs also exhibit several advantages, such as improved thermal effects, faster response rate, larger working temperature range, higher resolution, wider color gamut, higher contrast, lower power consumption, and operability at higher current density.

A micro LED display panel is manufactured by integrating an array of thousands or even millions of micro LEDs with an integrated circuit (IC) back panel. In conventional techniques, micro LEDs can be packaged on the IC back panel, where an array of micro LEDs forms a light-emitting area in a functional region on a front side of the IC back panel. Meanwhile, a non-functional area on the front side of the IC back panel can be used for electrodes, which can create an I/O port for voltage and signal transmission. This packaging arrangement results in a larger micro LED product, requiring more space, and thereby hindering its application in space-constrained products.

Therefore, there is a need for improving the packaging of micro LEDs.

Some embodiments of the present disclosure provide a micro LED display panel. The micro LED display panel includes a micro LED chip including a driving layer and a micro LED array disposed on the driving layer, the driving layer being configured to receive signals for driving the micro LED array; a flexible circuit board (FCB) disposed adjacent to the micro LED chip and configured to couple to the micro LED chip; a molded layer disposed on the micro LED chip and the FCB to join the micro LED chip and the FCB together, leaving an open region above the micro LED array; and a transparent cover disposed within the open region to shield a top surface of the micro LED array.

Some embodiments of the present disclosure provide a method of manufacturing a micro LED display panel, including coupling a flexible circuit board (FCB) to a micro LED chip having a driving layer and a micro LED array disposed on the driving layer, the driving layer being configured to receive signals for driving the micro LED array, the FCB being disposed adjacent to the micro LED chip and configured to couple to the micro LED chip; forming a molded layer to bond the micro LED chip and the FCB into a single structure, leaving an open region above the micro LED array; and disposing a transparent cover within the open region to cover a top surface of the micro LED array.

Some embodiments of the present disclosure provide a display device. The display device includes any of the micro LED display panels disclosed herein.

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise represented. The implementations set forth in the following description of exemplary embodiments do not represent all implementations consistent with the invention. Instead, they are merely examples of apparatuses and methods consistent with aspects related to the invention as recited in the appended claims. Particular aspects of the present disclosure are described in greater detail below. The terms and definitions provided herein control, if in conflict with terms and/or definitions incorporated by reference.

1 1 FIGS.A andB 2 FIG.A 1 FIG.A 2 FIG.B 1 FIG.A 1 1 2 2 FIGS.A,B,A andB 10 10 10 10 110 120 130 140 130 110 120 110 120 130 130 110 120 110 120 130 110 120 110 120 140 110 110 illustrate structural diagrams showing an exemplary micro LED display panel, according to some embodiments of the present disclosure.illustrates a structural diagram showing a sectional view of exemplary micro LED display panelalong section line A-A in, according to some embodiments of the present disclosure.illustrates a structural diagram showing a sectional view of exemplary micro LED display panelalong section line A-A in, according to some embodiments of the present disclosure. As shown in, micro LED display panelincludes a micro LED chip, a flexible circuit board (FCB)(e.g., a flexible printed circuit board), a molded layer, and a transparent cover. The manufacturing process includes creating molded layeron a portion of micro LED chipas well as FCB, so that micro LED chipand FCBare then joined together as a single compact structure. In some embodiments, the molding process can also be transfer molding, injection molding, compression molding, extrusion molding, hollow molding, etc. In some embodiments, the molding material of molded layercan be epoxy molding compound(EMC), acrylic (Polymethyl Methacrylate), acrylonitrile butadiene styrene (ABS), nylon polyamide (PA), polycarbonate (PC), polyethylene (PE), etc. This resulting assembly is diminutive and can be seamlessly incorporated into a display device. For example, during the deposition process, molded layerwith a high-temperature capability can be applied onto micro LED chipand FCB. At an elevated temperature, the molding material adopts a softer consistency, allowing it to envelop micro LED chipand FCB. After cooling and hardening, molded layereffectively encloses and bonds to micro LED chipand FCB, uniting micro LED chipand FCBas a cohesive entity. Furthermore, transparent covercan be disposed on or above micro LED chipto protect micro LED chip.

2 FIG.A 110 111 112 111 111 112 111 113 112 112 113 120 As shown in, micro LED chipincludes a driving layerand a micro LED arraydisposed on driving layer. Driving layermay include a driving circuit (not shown) for driving micro LED arraywith received signals. Specifically, driving layermay include a signal zonefor receiving the signals for driving micro LED arrayand passing the signals to the driving circuit. Micro LED arrayis not disposed on signal zonein order to provide space for leading out electrodes which can be coupled to electrodes within FCB.

10 120 113 10 110 120 110 120 130 110 120 110 120 130 For the compact structure of micro LED display panel, FCBcan be disposed adjacent to signal zoneto shorten a total length of micro LED display panel. A distance between micro LED chipand FCBcan be from one millimeter to several millimeters. In some embodiments, the distance between micro LED chipand FCBcan be set according to the adhesion of a molding material of molded layer, such that the assembly of micro LED chipand FCBwill not be broken by applied forces. It is appreciated that micro LED chipand FCBmay be disposed apart at a greater distance, in which case a thicker molding material may need to be used for molded layer, when the adhesion of the molding material is relatively low.

120 121 120 113 111 121 120 120 112 120 In some embodiments, FCBincludes a connection zonefor leading out electrodes. FCBcan be coupled to signal zoneof driving layerin connection zoneof FCB. As can be appreciated, FCBmay not generate the signals for driving micro LED array, but it can pass these signals and thus function as a medium for transmitting signals and power. These signals can be generated by a graphic processing unit (GPU) connected to FCB.

1 1 2 2 FIGS.A,B,A andB 2 FIG.A 130 110 120 121 120 130 110 120 110 120 130 150 1 110 120 111 110 120 130 110 120 130 150 2 112 112 130 110 120 112 With further reference to, molded layercan be disposed to bond to and join micro LED chipand FCB(e.g., connection zoneof FCB) into the single compact structure. As described above, molded layercan be disposed on a portion of outer surfaces of micro LED chipand FCBand bond micro LED chipand FCBtogether. More particularly, molded layercan be formed to fill a gap-between micro LED chipand FCBas well as formed on a side surface and a portion of a front surface of driving layeron which micro LED chipis formed, and an end portion of FCB. The integrated molded layerjoins micro LED chipand FCBinto the single compact structure. As shown in, molded layercan be disposed to leave an open region-above micro LED array, though which micro LED arraycan emit light representing images that are rendered according to the received signals described above. Herein, molded layercan join micro LED chipand FCBwithout affecting the display of micro LED array.

150 2 130 150 2 130 150 2 130 130 150 2 150 2 130 130 In some embodiments, open region-is formed with a specific shape having a periphery defined by molded layer. For example, open region-can be formed with a trapezoidal cross section and with an outwardly widening opening structure, or it can be formed with a rectangular cross section. During the deposition process to form molded layer, open region-can be occlued by a mold used to form molded layer. The molding material cannot be filled in a space occupied by the mold. When molded layerhardens, the mold can be removed to expose open region-. The outwardly widening opening structure or a rectangular cross section structure of open region-, defined by the periphery of molded layer, facilitates easier demolding. As can be appreciated, the mold can be removed upwardly without damaging molded layerthat has already hardened.

150 2 150 2 112 112 150 2 112 150 2 112 150 2 112 150 2 112 1 2 FIGS.A andA Moreover, the outwardly widening opening structure decreases undesired reflections by and between inside wall of open region-. Such internal reflections within open region-could blur the image rendered by micro LED array, which could deteriorate display quality. With the outwardly widening opening structure, most of the light from micro LED arraycan be emitted through open region-and reach a viewer's eyes directly. In some embodiments, some light from micro LED arraycan be emitted through open region-with limited reflections. As shown in, micro LED arrayis totally exposed from open region-. That is, the emitted light from micro LED arraycan be seen from above open region-within a certain viewing angle (e.g., within an angle range of eighty-five degrees from a central normal axis of micro LED array).

2 FIG.A 140 150 2 112 140 112 112 140 112 140 112 140 111 112 112 111 140 110 112 140 130 140 130 As shown, transparent covercan be disposed within open region-to shield a top surface of micro LED array. That is, transparent covercan be disposed on or above the top surface of micro LED arrayto protect micro LED array. For example, transparent covercan be disposed directly on the whole top surface of micro LED array, or transparent covercan be spaced from the top surface of micro LED arrayat a distance from 1 μm to 500 μm. In some embodiments, transparent covermay include an adhesive layer (not shown) that is adhered to driving layer, around the top surface of micro LED array. Although the adhesive layer can be transparent to light, it may absorb the light emitted from micro LED arrayto some extent. By disposing the adhesive layer onto driving layer, transparent covercan be secured to micro LED chipwithout affecting the light efficiency of micro LED array. In some embodiments, the adhesive layer can be formed by epoxy adhesive, thermosetting adhesive, moisture adhesive, etc. In some embodiments, transparent coverdoes not contact molded layer. Specifically, a side surface of transparent coveris spaced from molded layerat a distance from 1 μm to 1000 μm.

3 3 FIGS.A andB 3 3 FIGS.A andB 3 FIG.A 3 FIGS.A 3 FIG.A 110 10 130 140 110 112 111 111 111 1111 113 111 112 1111 112 1111 3 112 1111 1111 112 illustrate a structural diagram showing micro LED chipof exemplary micro LED display panel, according to some embodiments of the present disclosure. For a clear illustration of the circuitry structure, some of the components shown inmay not be viewable from outside and are shown with dashed lines. As shown in, molded layerand transparent coverare omitted for a better understanding of the layout of micro LED chip. Micro LED arraycan be formed on a surface of driving layerand coupled to driving layer. In addition, driving layermay include metal padsarranged in signal zoneon the same surface of driving layeron which micro LED arrayis formed. Some of metal padscan be coupled to corresponding electrodes of micro LED arrayfor coupling therebetween. Due to the property of metals, metal padscan reflect light incident on them (denoted as “incident light” inandB). Some of the light emitted by micro LED arrayis inevitably incident on metal pads, for example, by single or multiple reflections. Such reflected light (denoted as “reflected light” in) from metal padsmay blur and deteriorate the images rendered by micro LED array.

3 FIG.B 1 2 2 FIGS.A,A andB 1112 1111 111 1112 112 1112 1112 1112 140 1114 140 1112 112 1114 1112 140 130 1112 To prevent this, as shown in, a light shading layercan be further disposed on metal padsof driving layer. Light shading layercan absorb light incident thereon and thus improve the quality of the images rendered by micro LED array. For example, light shading layercan be black photoresist and its thickness can be several microns. In some embodiments, light shading layercan also be light-shielding film with black or dark color. In some embodiments, light shading layercan be adhered to transparent cover. For example, an adhesive layerof transparent covercan be adhered to light shading layerand around the top surface of the micro LED array. As can be appreciated, adhesive layerdisposed on light shading layerneed not be transparent. In addition, as the side surface of transparent covercan be spaced from molded layer, light shading layercan be viewed from directly above as shown in.

3 FIG.A 3 FIG.B 3 FIG.B 2 FIG.A 2 FIG.B 2 FIG.B 2 FIG.A 1111 112 1112 112 112 130 1112 1111 112 150 2 1112 150 2 1112 112 160 1112 1112 160 1112 112 1112 112 130 1112 1112 130 1112 1112 In some embodiments, as shown in, at least some of metal padscan be formed around micro LED array. Light shading layerincan also be formed around micro LED arraywithout leaving a gap between micro LED arrayand molded layer(not shown in). That is, light shading layeris formed to cover all metal pads, and any region other than micro LED arrayexposed on open region-can be shielded by light shading layerwhen viewed from above open region-. A height of light shading layercan be the same as a height of micro LED array. As used herein, a height of an object is a distance of the highest part of the object from a reference plane (e.g., a bottom surface of a substrate layerwhich is described below). For example, the height of light shading layeris the distance between a top surface of light shading layerand a back surface of substrate layer. In this regard, the top surface of light shading layercan be aligned with the top surface of micro LED array. In some embodiments, as shown in, the height of light shading layercan be higher than the height of micro LED array. In some embodiments, molded layercan be disposed adjacent to light shading layerbut not on light shading layer. In some embodiments, molded layercan be disposed adjacent to and on light shading layer, as shown in. As can be appreciated, the height of light shading layershown incan be different from that shown in.

3 FIG.C 3 FIG.C 2 2 FIGS.A andB 180 124 180 112 illustrates a structural diagram showing a micro LED chip of another exemplary micro LED display panel, according to some embodiments of the present disclosure. As shown in, a plurality of electrodescan be used to lead out tracesshown in. As can be appreciated, electrodesare connected to micro LED array.

1 2 2 FIGS.B,A andB 10 160 130 110 120 130 110 121 120 160 160 110 120 160 130 130 130 160 160 160 160 With further reference to, micro LED display panelfurther includes substrate layer, which is disposed cooperatively with molded layerto join micro LED chipand at least a portion of FCB. For example, molded layer, micro LED chip, and connection zoneof FCBcan be disposed on a front surface of substrate layer. Substrate layer, on one hand, can provide mechanical rigidity to surface components (e.g., micro LED chip, FCB, etc.) disposed thereon. On the other hand, substrate layercan be adhered to molded layerwhen molded layercools and hardens. As such, molded layer, along with substrate layer, can provide a sealed or semi-sealed environment for the surface components. In some embodiments, substrate layercan be formed by a steel plate. As can be appreciated, other materials can also be used to form substrate layer, as long as they can provide functionality similar to the steel plate. For example, substrate layercan also be formed by ceramics, hard resin, etc.

110 120 110 120 In some embodiments, a bottom surface of micro LED chipcan be aligned with a bottom surface of FCB. That is, a height of the bottom surface of micro LED chipcan be the same as the bottom surface of FCB.

2 FIG.A 120 122 160 122 110 122 110 160 122 110 122 120 160 10 120 160 120 120 122 120 In some embodiments, as shown in, FCBmay include an adhesive layerthat is adhered to the front surface of substrate layer. A bottom surface of adhesive layercan be aligned with a bottom surface of micro LED chip. That is, adhesive layerand micro LED chipcan be attached to substrate layerwhich is a planar plate. In some embodiments, the bottom surface of adhesive layermay not be aligned with the bottom surface of micro LED chip. In some embodiments, adhesive layercan be conductive and its thickness can be from 5 μm to 50 μm. By this arrangement, FCBcan electrically couple to substrate layerwhich can be a common equipotential component in a display device including micro LED display panel. For example, FCBcan be connected to the ground when substrate layeris connected to the ground. Although not shown, FCBmay include a conductive line which acts as a ground wire and couples to ground potentials of the components connected to FCB. In some embodiments, adhesive layercan be electrically isolated while the FCBneed not to be connected to the ground.

111 1113 160 1113 120 1113 122 1113 111 160 111 111 1113 1113 120 In some embodiments, driving layerfurther includes an adhesive layerthat is adhered to the front surface of substrate layer. A bottom surface of adhesive layercan be aligned with a bottom surface of FCB. Specifically, the bottom surface of adhesive layercan be aligned with the bottom surface of adhesive layerif present. In some embodiments, adhesive layeris insulative and electrically isolates driving layerfrom substrate layer. As driving layermay include several electrodes or solder points on its bottom surface, the back surface of driving layermay need to be insulated from the external environment. For example, adhesive layercan be formed by a Die Attach (DA) adhesive or Die Attach Film (DAF) adhesive. In some embodiments, the bottom surface of adhesive layermay not be aligned with the bottom surface of FCB.

122 1113 122 1113 In some embodiments, a thickness of adhesive layercan be similar to a thickness of adhesive layer. In other embodiments, the thickness of adhesive layercan be less than the thickness of adhesive layer.

122 121 160 121 122 122 123 121 160 123 121 122 121 123 120 120 160 121 130 160 2 FIG.A 2 FIG.A In some embodiments, adhesive layeris merely disposed on a bottom surface of connection zone, while substrate layercan be disposed below connection zonevia adhesive layer. In some embodiments, as shown in, adhesive layercan be further disposed below a bottom surface of a regionadjacent to connection zone, while substrate layeris further disposed below regionadjacent to connection zonevia adhesive layer. Boundaries of connection zoneand regionare shown as dashed lines in. As FCBis flexible and may be relatively fragile, disposing a longer region of FCBon substrate layercan enhance its reliability in the encapsulation of connection zonecreated by molded layerand substrate layer.

130 120 1 121 130 120 130 120 120 130 160 1 121 2 123 121 1 2 1 2 2 FIG.B In some embodiments, molded layercan be further formed on FCBat a distance Lextending from connection zone. As can be appreciated, a longer disposition of molded layeron FCBincreases adhesion between molded layerand FCB. It can enhance reliability of FCBin the encapsulation created by molded layerand substrate layer. In some embodiments, the distance Lextending from connection zonemay be equal to or differ from length Lof regionadjacent to connection zone. For example, as shown in, the distance Lcan be longer than length L(e.g., the distance Lcan be 0.05 mm longer than length L).

120 124 121 120 113 124 130 124 124 113 121 2 FIG.A 2 FIG.B In some embodiments, FCBincludes conductive tracesthat are led out from connection zone. FCBcan be coupled to signal zonevia traces. In some embodiments, as shown in, molded layercan be further disposed to encapsulate traces. In some embodiments, tracesmay include a bunch of wires that are led out from different places of signal zoneand connection zone, as shown in.

130 112 130 112 130 10 In some embodiments, a height of molded layeris higher than or equals to a height of micro LED array. A higher molded layercan provide extra protection to micro LED array, while a lower molded layercan provide a more compact design of micro LED display panel.

1 FIG.A 130 121 130 121 130 120 130 120 121 120 121 120 In some embodiments, as shown in, a width W of molded layercorresponds to a width of connection zone. That is, the width of molded layermay basically be equal to the width of connection zone, ignoring the manufacturing tolerance and a thin deposition of molded layerat edges of FCB. In some embodiments, the width of molded layercan be greater than all regions of FCBother than connection zoneof FCB. In other words, connection zoneis the widest area within FCB, so as to guarantee the rigidity of the connected two parts.

1 1 2 2 FIGS.A,B,A andB 10 170 121 120 120 170 170 1701 1702 1703 1701 1702 1703 In some embodiments, as shown in, micro LED display panelmay include a hard circuit boardprovided at an opposite end to connection zoneon FCB, and electrically coupled to FCB. Hard circuit boardmay include one or more connectors. In this example, hard circuit boardincludes connectorsandat one surface and a connectorat an opposite surface. Connectors,andcan be connected to other hard circuit boards of other micro LED display panels or other processing units with pin-slot connections. Herein, the connectors are not specified as pin-slot configuration, as long as they can be used for I/O communication with external devices.

4 FIG.A 4 FIG.B 40 40 40 10 40 460 460 170 10 460 4602 460 4602 4602 460 4601 4602 4601 4601 4602 4602 4601 4602 40 40 illustrates a structural diagram showing a front side of another exemplary micro LED display panel,illustrates a structural diagram showing a back side of exemplary micro LED display panel, according to some embodiments of the present disclosure. Micro LED display panelshows much in common with micro LED display paneldescribed above. However, micro LED display panelincludes a hard circuit board. In some embodiments, hard circuit boardmay have a shape and functionality different from hard circuit boardof micro LED display panel. Specifically, hard circuit boardincludes a memory chip. In some embodiments, hard circuit boardmay further include a cover arranged on or above memory chipfor protecting memory chip. Hard circuit boardalso includes a connectorat one surface and memory chipat an opposite surface to connector. Connectorand memory chipare connected together for storing data into and outputting data from memory chipthrough connector. For example, memory chipmay cache or store patterns to display or instructions for displaying patterns for micro LED display panel, which may reduce the communication cost between micro LED display paneland a signal source (for example, a GPU), thereby improving display efficiency

10 1701 1703 40 40 10 10 1701 1702 1703 1 1 2 2 FIGS.A,B,A andB 1 1 2 2 FIGS.A,B,A andB 1 1 2 2 FIGS.A,B,A andB Micro LED display panelwith connectorstoon two surfaces shown incan be used as a hub for connecting with micro LED display panel. The other aspects of micro LED display panelcan be understood by referring to the description of micro LED display panelwith reference to, and will not be described in detail here. It can be understood that micro LED display panelwith reference tocan further include a memory chip coupled with one or more of connectors,,.

5 FIG.A 1 1 2 2 FIGS.A,B,A andB 4 4 FIGS.A andB 5 FIG.B 5 5 FIGS.A andB 50 501 10 502 503 40 50 illustrates a front side of an exemplary display devicehaving a micro LED display panel(e.g., corresponding to micro LED display panelin) and micro LED display panelsand(e.g., each corresponding to micro LED display panelin),illustrates a back side of exemplary display device, according to some embodiments of the present disclosure. For a clear illustration of coupling relationships between connectors, some of the components shown inmay not be viewable from outside and are shown with dashed lines.

5 FIG.A 5 FIG.B 4601 502 503 1701 1702 501 50 502 503 4601 502 503 1701 1702 501 501 1703 501 1703 501 502 503 501 502 503 As shown in, connectorsof micro LED display panelsandare inserted into connectorsandof micro LED display panelrespectively, which forms exemplary display devicehaving three collaborative micro LED display panels. More particularly, panelsandcan be turned over by twisting respective FCB's, so that connectorsof panelsandface connectorsandof micro LED display panel, respectively. These micro LED display panels can be driven by signals received from micro LED display panel, specifically through connectoron a back side of micro LED display panel, as shown in. Connectorcan be connected to an external device that generates the signals. As can be appreciated, micro LED display panels,, andcan be used to display red components, green components, and blue components of a composite image, respectively. That is, micro LED display panelmay render a red image, micro LED display panelmay render a green image, and micro LED display panelmay render a blue image.

6 FIG. 6 FIG. 5 5 FIGS.A andB 60 600 60 501 502 503 600 600 501 502 503 60 illustrates another exemplary display devicehaving a combiner, according to some embodiments of the present disclosure. Referring to, display device(e.g., a polychrome projector) includes micro LED display panel, micro LED display panel, and micro LED display panel, shown in, and a combiner(e.g., a combining prism). Combinercan be used to combine (also referred to as “compositing”) the images rendered by micro LED display panel, micro LED display panel, and micro LED display panelinto a composite image. As will be appreciated, display devicemay also include other necessary components for operation that are omitted here.

501 502 503 600 600 As described above, micro LED display panelmay render a red image, micro LED display panelmay render a green image, and micro LED display panelmay render a blue image, which can be composited through combinerto form a polychrome image. The red image, the green image, and the blue image can be aligned after passing through combinerto form the polychrome image.

110 111 112 110 110 112 112 110 112 2 3 FIGS.A andA In some embodiments, micro LED chipincludes an integrated circuit (IC) backplane (e.g., driving layershown in). Micro LED arrayincludes multiple micro LEDs (not shown). Each micro LED may form at least a portion of a pixel element on micro LED chip. For example, the pixel element can be formed by a single micro LED for a monochrome display, and can be formed by three micro LEDs for a color display. In some embodiments, each dimension of micro LED chipis not more than 1 centimeter (cm), preferably, not more than 20 micrometers (μm). A resolution of micro LED arraycan be 720×480, 640×480, 1920×1080, 1280×720, 2K (i.e., 2048×1080), or 4K (i.e., 3840×2160). A diameter of the micro LED is at a nanometer level, e.g., 20 nm to 100 nm. In some embodiments, the pitch of micro LED array, i.e., the minimum center-to-center distance between adjacent micro LEDs, may range from 2 μm to 50 μm. In some embodiments, the number of pixels in micro LED chipmay range from several thousands to over several millions. In some embodiments, micro LED arraymay include blue micro LEDs, green micro LEDs, or red micro LEDs.

112 110 In some embodiments, the IC backplane may be electrically connected to each micro LED of micro LED arraythrough separate metal interconnects. In some embodiments, each micro LED may be separately, electrically controlled by the IC backplane. In some embodiments, the IC backplane may be electrically connected to an electrode of micro LED chipthrough a metal interconnect. In some embodiments, a dielectric layer may be formed in the gap between the micro LEDs. In some embodiments, the dielectric layer may also be formed in the gap between metal interconnects.

112 In some embodiments, each micro LED of micro LED arraymay include a micro mesa structure. In some embodiments, the micro mesa structure may include a first type epitaxial layer, a light emitting layer, and a second type epitaxial layer, from bottom up. That is, among the three layers, the first type epitaxial layer is closest to the IC backplane; the light emitting layer is on top of the first type epitaxial layer and is further away from the IC backplane; the second type epitaxial layer is on top of the light emitting layer and is the furthest away from the IC backplane. In some embodiments, the light emitting layer is formed by several stacked quantum well layers, especially super crystal stacked quantum well layers. Preferably, the super crystal stacked quantum well layers include multiple pairs of a quantum well layer stacked with a quantum barrier layer. In some embodiments, the first type epitaxial layer is a semiconductor material with a first conductive type and includes several semiconductor layers. The main body material of the first type epitaxial layer can be but not limited to base materials including one or more of Ga, N, As, P, In, or Al etc. Additionally, the first type epitaxial layer can, from up to bottom, comprise but not limited to a waveguide layer, a limitation layer, a transition layer, and a window layer. Furthermore, an ohmic contact layer can be formed under the window layer. In some embodiments, the second type epitaxial layer is a semiconductor material with a second conductive type and includes several semiconductor layers. The main body material of the second type epitaxial layer can be but not limited to base materials including one or more of Ga, N, As, P, In, or Al etc. Additionally, the second type epitaxial layer can, from up to bottom, include but not limited to a limitation layer, and a waveguide layer. Furthermore, in some embodiments, an ohmic contact layer can but not limited to be formed on the limitation layer.

112 112 112 112 112 In some embodiments, a top conductive layer may be formed on a top surface of micro LED array. In some embodiments, the top conductive layer may be shared by all micro LEDs of micro LED array. In some embodiments, micro LED arraymay include a single layer of micro LEDs. For example, the micro LEDs can be arranged on a plane. In some embodiments, micro LED arraymay include multiple layers of micro LEDs vertically stacked with electrical connection layers. Each micro LED of micro LED arraycan be respectively controlled by separately controlling an anode and a cathode of each micro LED, or by controlling a common anode electrode layer and respective cathodes of the micro LEDs, or by controlling a cathode electrode layer and respective anodes of the micro LEDs. For example, the micro LEDs can be arranged on several planes which are parallel to each other.

7 FIG. 7 FIG. 70 70 702 704 illustrates a flowchart of an exemplary methodof manufacturing a micro LED display panel, according to some embodiments of the present disclosure. As shown in, methodincludes stepsand, which can be implemented by a manufacturing device (e.g., a manufacturing device including a die attach machine, a wire bonding machine, a molding machine, a cutting machine, etc.) for making micro LED display panel.

702 1 6 FIGS.A to In step, the manufacturing device may couples a flexible circuit board (FCB) to a micro LED chip. As described in connection with, the micro LED chip comprises a driving layer and a micro LED array disposed on the driving layer. The driving layer may comprise a signal zone on which the micro LED array is not disposed. The signal zone may be used to receive signals for driving the micro LED array. In addition, the manufacturing device may dispose the FCB adjacent to the signal zone and couple it to the signal zone in a connection zone of the FCB.

702 In some embodiments, the FCB includes conductive traces that lead out from the connection zone. The FCB can be coupled to the signal zone via the traces. In step, a molded layer is further disposed to encapsulate the traces.

704 In step, the manufacturing device forms the molded layer to bond the micro LED chip and the FCB into a single compact structure, and leave an open region above the micro LED array.

706 In step, the manufacturing device may dispose a transparent cover within the open region to cover a top surface of the micro LED array.

70 In some embodiments of the present disclosure, methodmay further include a step of disposing a light shading layer on metal pads arranged in a signal zone on a front surface of the driving layer, which can be implemented by the manufacturing device.

70 704 In some embodiments of the present disclosure, methodmay further include a step of disposing a substrate layer cooperatively with the molded layer to join the micro LED chip and at least a portion of the FCB, which can be implemented by the manufacturing device. This step can be implemented before disposing the molded layer in step. In this step, the molded layer, the micro LED chip, and the connection zone of the FCB can be disposed on a front surface of the substrate layer.

70 1 6 FIGS.A to The other aspects of methodcan be understood by referring to the description above with reference to, and will not be described in detail here.

Some embodiments of the present disclosure also provide a display device. The display device may include any of the micro LED display panels described herein.

8 FIG. 8 FIG. 1 1 2 2 FIGS.A,B,A andB 4 4 FIGS.A andB 800 810 820 810 800 800 810 800 810 810 810 10 40 illustrates an exemplary display device, according to some embodiments of the present disclosure. As shown in, a near eye display (NED), for example AR glasses, includes a pair of polychrome projectorsand a framefor securing polychrome projectors. NEDmay also include other components which are omitted here for the purpose of clearly illustrating the configuration of NED. Each polychrome projectorcan be arranged at an end of a temple (not shown) of NED, respectively. A power system and a processing system to drive polychrome projectorscan be embedded in the temple. Images rendered by each polychrome projectorcan be captured by respective eyes of a viewer (not shown), which can be used to create a virtual scene or an augmented scene for the viewer. In some embodiments, the term “render” may also be referred to as “display,” “show” or an equivalent. Each polychrome projectormay include three micro LED panels (e.g., each corresponding to micro LED display panelin, or micro LED display panelin) of different colors and a combiner (e.g., a combining prism). The combiner can be used to combine (also referred to as “compositing”) the images rendered the three micro LED panels into a composite image.

9 FIG. 9 FIG. 1 1 2 2 FIGS.A,B,A andB 4 4 FIGS.A andB 900 910 10 40 900 900 illustrates another exemplary display device, according to some embodiments of the present disclosure. As shown in, a head-mounted virtual reality deviceincludes two micro LED panels(e.g., each corresponding to micro LED display panelin, or micro LED display panelin). Although not shown, head-mounted virtual reality devicemay also include a central processing unit (CPU), a graphic processing unit (GPU) acting as a signal source, and other related circuitries. The introduction of micro LED panels that embody the micro LED elements described above in head-mounted virtual reality devicecan improve the lighting efficiency thereof, hence reducing energy consumption and improving imaging quality.

It should be noted that the relational terms herein such as “first” and “second” are used only to differentiate an entity or operation from another entity or operation, and do not require or imply any actual relationship or sequence between these entities or operations. Moreover, the words “comprising,” “having,” “containing,” and “including,” and other similar forms are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items.

As used herein, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, if it is stated that a database may include A or B, then, unless specifically stated otherwise or infeasible, the database may include A, or B, or A and B. As a second example, if it is stated that a database may include A, B, or C, then, unless specifically stated otherwise or infeasible, the database may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

In the foregoing specification, embodiments have been described with reference to numerous specific details that can vary from implementation to implementation. Certain adaptations and modifications of the described embodiments can be made. Other embodiments can be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims. It is also intended that the sequence of steps shown in figures are only for illustrative purposes and are not intended to be limited to any particular sequence of steps. As such, those skilled in the art can appreciate that these steps can be performed in a different order while implementing the same method.

In the drawings and specification, there have been disclosed exemplary embodiments. However, many variations and modifications can be made to these embodiments. Accordingly, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.